Page 202 - Applied Photovoltaics

x aesthetics—colour, size, shape, tilt, pattern, transparency
x solar access—current and future shading, partial, complete or time of day,
from trees or buildings
x building codes—roof structure, strength of mounting, zoning for generation,
light reflection
x insurance issues—fire resistance, roof loading, safety, damage to grid or
other utility users
x maintenance—routine and emergency, component replacement
x impact on utility—overloading distribution transformers, power factor,
harmonics, isolation of PV (DC) current, disconnection mechanisms,
grounding, metering
x contract with utility—buyback rates, equipment approvals, billing
arrangements.

10.3 UTILITY APPLICATIONS FOR PHOTOVOLTAICS

The potential for utility use of PV is wider than merely central generation. Utility
familiarity with PV usage could be gained via some of the following, smaller scale
applications (Sandia National Laboratories, 1990; Bigger et al., 1991):
x Distribution feeder voltage and energy support—for relieving thermal
overload on transformers and conductors by reducing localised peak daytime
current flows. The use of PV could delay or eliminate more expensive line
reconditioning, substation transformer replacement or new circuit
construction to serve overloaded areas. At critical transmission and
distribution points it could also reduce electrical losses, provide kVAR
support, increase reliability of supply and increase the effective capacity
value of the PV system. The use of PV in such situations can double the value
of the PV system, compared to the value attributed to energy and capacity
savings alone.
x Transmission tower beacons—for powering these beacons, which are
required on all towers more than 60 m high and close to airports.
x Transmission sectionalising switches—for isolating portions of distribution
or transmission lines for maintenance or power flow optimisation. In the
USA, for example, such remotely-operated switches are used about every
30 km and many could be converted to PV.
x Street and security lighting—for meeting municipality and government
agency requirements.
x Rest area fans and lights—for parks, roadside convenience facilities and
boat launching sites in remote or environmentally-sensitive areas.
x Remote water pumping—for new systems as well as to replace wind-
powered systems or power line replacements.
x Power supply to remote residences—for customers who would not
otherwise receive utility supply, particularly small users, such as individual
houses or vacation homes.
x Grid security—to provide reliable PV-battery power supply or backup for
critical supervisory control and data (SCADA) in electricity, gas and oil
supply systems (Varadi & Braun, 2003). It can sometimes be more cost-

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